William Wallace wrote:You have got to be careful when sharpening any tool with a grinder. The high speed of the grinder could pull any heat treatment away from a blade.
Dan Grubbs wrote:GOOD edge tools have had temperature management used in their creation. There's not only the heating, but how the steel is cooled once heated, both are factors with various tools. I agree with William in that a bench grinder can be a challenge when using them to shape or sharpen edge tools. Most people trying to hone an edge on a cutting tool with a bench grinder would raise the temperature of the steel too high. This will actually change the structure of the steel and may cause the edge to fail, or even the entire tool to fail. However, some cheap tools have been frequently sharpened on bench grinders to the satisfaction of the user. I confess to putting a new primary bevel on my garden hoe with a bench grinder, but to shape and sharpen the cutting edge I use a file. For gross tools, such as a hoe or spade, I've seen people use a grinder to hone the cutting edge. It doesn't last long due to what the tools are used for. The issue would be safety in my mind. Putting a cutting tool in motion while in use and it fail could eject shards or pieces of the tool when it comes in contact with something else. A file is just fine to put a sufficient cutting edge on gross tools. For fine tools, such as axes, large knives, a kukri, a machete, etc., I would favor a puck stone to hone the edge. For finer knives, I would use the wet stones.
You'll discover there are some very strong opinions on knife sharpening. It's a deep hole with turbulent waters if you decide to jump in. You've been warned.